New Zealand warned international health authorities Saturday of exported dairy products, including infant formula, containing a bacteria that could lead to botulism -- a potentially fatal illness.

The government said the contaminated whey protein concentrate, or products using this ingredient, had been exported to Australia, China, Malaysia, Saudi Arabia, Thailand and Vietnam.

Dairy giant Fonterra, which manufactured the product more than a year ago, said eight customers had been advised and were investigating whether any of the affected product was in their supply chains.

If necessary, contaminated consumer products would be recalled, the company said in a statement.

China Saturday said it had contacted New Zealand's embassy and asked them "to take measures to prevent the products in question from influencing the health of Chinese consumers".

In a statement posted on its website, China's General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ), said it had ordered importers to withdraw any contaminated products and called on quarantine officials to step up inspections of dairy products imported from New Zealand to China.

There have been no reports of any illness linked to consumption of the affected whey protein.

New Zealand Trade Minister Tim Groser said health authorities around the world, including the World Health Organization, had also been alerted to the contamination.

"As soon as New Zealand authorities were notified of this risk, we immediately acted to inform relevant authorities around the world," Groser said.

"This has included formally notifying Infosan, the World Health Organization's international food safety regulators network. As more information on this issue is confirmed we will provide our trading partners with further updates.

"We understand that the markets to which contaminated whey protein concentrate, or products using this ingredient, has been exported are Australia, China, Malaysia, Saudi Arabia, Thailand and Vietnam."

Fonterra said the affected product was used in a range of drinks including infant formula and sports drinks.

"We are doing everything we can to assist our customers in ensuring any product containing this ingredient is removed from the marketplace and that the public is made aware," Fonterra chief executive Theo Spierings said.

Three batches of whey protein concentrate manufactured in May last year recently tested positive for Clostridium botulinum.

The batches have been used to form 870 tonnes of products sold in a variety of markets, the Ministry for Primary Industries' Acting Director General Scott Gallacher said.

The symptoms of botulism include nausea, vomiting and diarrhoea, followed by paralysis, and it can be fatal if not treated.

Fonterra said the potential impact on someone consuming a contaminated product would depend on their age and the amount they consumed.

For an adult, a small amount of contaminated whey protein "would probably pass through unnoticed", Fonterra's managing director of New Zealand milk products, Gary Romano, told reporters.

Dairy exports are New Zealand's major earner and its products are particularly popular in Asia, where they are considered the gold standard.

According to government data the dairy industry contributes 2.8 percent to New Zealand's GDP and about 25 percent of its exports. It is worth NZ$10.4 billion (US$8.1 billion) annually.

New Zealand accounts for one-third of the world's cross-border trade in dairy products.

Fonterra, the world's largest dairy exporter, reported revenues of NZ$19.8 billion ($15.5 billion) in the 2012 financial year.